While working on this project, we were interested in finding other approaches comparable to ours for inspiration. However we could not find a visualization with the kind of scope and level of interaction that we were envisioning.

One similar visualization made by the World Fish Center \cite{wfc, fishbase}, provides information about different kind of fish species. This is accomplished by static, standardized distribution maps for currently 8,000 different species of fish, marine mammals and invertebrates. A narrow color scheme going from yellow to red is used to illustrate population density in the map. The data set can be restricted to obtain a map visualizing the population density for a subset of all species. Unfortunately, the visualization is not interactive and the evolution of the population over time is also not shown.

The work of the World Fish Center is focused on providing information only for fish, marine mammals and invertebrates, in contrast to our visualization, which aims to be more generic.

Another approach to visualizing this kind of data was put forth by the California Avian Data Center \cite{cadc}. Interactive maps are used to represent data about bird observations in a cumulative manner as well as the distribution of different species. The visualization is based on Google maps and uses overlays to display the information on the map. On some of the maps, clicking will open a window with additional information. The visualization is confined to the state of California.

There are other visualizations related to animals available, however they are either less related to our approach than the examples discussed above, or similar enough that nothing is gained from adding them.